This invention relates to an apparatus for the dosed, continuous and simultaneous infusion of several infusion solutions or medicament solutions in accordance with the preamble of the main claim.
During the infusion of medicament solutions or infusion solutions, specific volume quantities are supplied to a patient at a given time unit by operating an infusion pump. For reasons of operational reliability and for the patient,s medical safety, the amount of solution to be supplied must strictly be adhered to. High demands are therefore made on the technical safety equipment of such an apparatus.
Under certain conditions the volume amount to be respectively supplied to a patient must strictly be observed, i.e both an increase in and a reduction of the amount must be prevented. As a result of these requirements, the technical equipment is very complicated and expensive. The attempt has therefore been made to somewhat lower the requirements and to simplify the construction of the whole safety equipment. With specific kinds of solutions to be supplied to a patient, or with specific medical indications, a solution amount smaller than the predetermined solution amount to be supplied to a patient is acceptable. The resultant medical risk is considered to be small, as the supply of a reduced amount can be easily detected and compensated for in routine checks carried out by the operating personnel or with the aid of other technical monitoring possibilities. Hence, it is possible to compensate for the effects caused by the supply of a reduced amount by taking specific measures within a greater time interval.
By contrast, many applications strictly forbid the uncontrolled supply of excess amounts of solutions to be administered to a patient. The delivery of excess amounts may be due to technical defects in the apparatus or may result from typical operating mistakes made by the personnel. While technical defects in the apparatus can be detected with the aid of a flow meter and the system can be shut off in emergency cases, or an alarm signal may be given, additional constructional steps must be taken for preventing operating errors.
During operation risks arise especially at the beginning, during an intended interruption or upon completion of the infusion process. If there is a free passage of the corresponding flexible tubes or catheters in these operational states, an uncontrolled amount of infusion solution may flow into the patient,s body due to the action of gravity. This danger exists when an infusion conduit is put into the infusion pump at the beginning of the infusion step. It also exists when the infusion process is interrupted or stopped or when the infusion conduit is to be removed from the pump at the same time.
German Utility Model 79 13 478 shows an infusion pump where a mechanical safety system is provided in the area of the door mounted on the housing for preventing the door from being closed as long as the flexible tube is not completely and correctly positioned. This mechanical system merely prevents the closing of the door, but is not capable of detecting an unintended opening of the door. In the last-mentioned case the flexible tube may come loose and slip out while the pump is operated. German patent application 33 29 977 published Mar. 7, 1985 discloses a multi-infusion arrangement wherein a valve is respectively arranged after a supply reservoir. Downstream of the valve, a conduit is guided to one common infusion pump which conveys all fluid flows from the supply reservoirs to a patient. Although it is here possible to close the feed line between the supply reservoir and the common infusion pump by means of the individual valves, fluid can freely flow to the patient when the pump is unintentionally opened, as there are no shut-off mechanisms.